Expanding-pulley variable-speed gear



Allg 19, 1952 G. RUEGENBl-:RG

EXPANDING-PULLEY VARIABLE-SPEED GEAR Ali-:Ill nml? Filed July 8, 1949 VILA IIL

. Idle/#laf Patented Aug. 19, 1952 :5. 1

foitifriealtteeenberg, Krefeld; Germany being mounted o'nthedr-iving shaft andtheother one on theldri-ven shaft. l The# axial movement. of

the-bevel discs', in order tok bring aboutY avariation vof speed is `caused-,as far as alreadyV known constructions are concerned, by a-mechanismfoperatedat willfforinstance ley-hand.

This invention concerns an expandingepulley variable speed gear of the aforesaid type, but ac cording to the-'present invention, both pairs of bevel discs are arranged to be axially movable and are-combined with means which automati- 'cally :regulates the position of the tvvolv pairs of bevel discs; vmomnted on the driving andi on the driven shafts respectively, when the turning moment' derived from'itliedriven shaft #is changed. Thereby results a Arespectivel adjustment of the driving member and atv the same time a-- speed adapted''to'V the alteredfturning moment ofthe vpair of bevel discs' mounted' on the driving shaft.

In a practical example ofthe inventionthe Vpairs of bevel discs mounted on theA driving' and on the driven shafts are not only axially movable but. are 'also 'rotatably arranged, the'discs bearing against elastic'or'resilient spring members or other' elastic members which are connected with their: respective shafts.

Itis, preferable'that th'e bevelv discs mounted on the driving` 'shaft are 'connected (with this shaft biy 'wound `(helical) bending stress-absorbing springs, especially Woundspr'ihg's', through'which the driving torque is conveyed,v Vvvlfiileuponthe bevel discs on the delivery shaft laterally curved surfaces are arranged.' These lateral curved surfaces may'bea'r against.l (supported)` rotary inem-` be'r's fixed to ythe driven" shaft, o'r the 4bevel discs may bear against curved surfaces connected to the driven shaft. 'The axial vgradient of the curved surfaces is suitably variably arranged'corresponding. to the changeable diameter of the running surface of the driving discs'.HV For the transmission 'of'. the turning moment different kinds of driving mechanism can be used, for instance cone belts, joined cone belts, chain-like members, for example laminated chains 'or-belts, jointed cone chains or the like.

For the purpose of better and fuller understanding,y the invention will noW be further des scribed vwith reference 'tof the accompanying drawings which diagrammatically illustrate the 5r` claires, l(ci. 74523017) improved device and itsdetails. by way of example. v

In :the drawing:

Figure lisa cross sectional view of thegear when verylittle or no DO Wer is being transmitted, and,

Figures Y2 and 3- each show a detail 'from different points-of View.,v i

I is the drivingshaft the. respective ends of whichere. mountedinhalt bearings? and.; 1'. and said Shaiterries; two lbevel .d-ics'y tand :,.The discs 4 and 5; are rotatably mounted onthe-shaft so; that they; can .be .axially moved byifpre.- stressed-exohangealblef helical springs '6 and 'I Whichare Yaxially `arranged.,around .Shaft ,land Whichurge the-bevel discs 4 andStOWards each othen In thevv positionv ofthe 1fgea1-,wherr-very little or no power is being transmitted: both oi the bevel discs bear against eachl other atA their centres, .This,positiorrcorrespondsto thee-maxii mum runnngsurfacezdiameter, iniwhichi-'casa the driving powerof the driving-.member I4 isa minimum.. The springs. "6;v randfl" bearat, .their other ends against. bushes .iB-s and 9i which are .mounted on the driving :shaft I sdajsi to permit theirV being.

moved inthe direction of the faxis and which. are slidinglv mountedionltheshaftl bymeans of keys:v '.l and. l l.. `'flilurthernio'rie,.nuts.I Zand i3.- are provided on. the. drivln'gfshaftd ,iforisecuring the springs 6 land' -1 inbositionagainst.allmovements inthe axial direction. Thesesprings. B and 1 may receive aipred'etermined. stressby a suitable adjustment ofthe nuts .l1-2l'y andi-i3 respectively. Atl therl saine time?the/'endsv ofA the. springs fsf and 'ldrivingly engagethediscsi', 'Sland the bushes sc -th'at-thesprings serve. to transmit the turningmoment-ironithe bushes" Band i?y tothe VAbevel discs "fl land 5 respectively; #Forfthis'purpose Ythe ends ofthefspring are -tuined'ini the axial direction 'and introduced-'into respective openings or 'recesses in the bushes- 8, `9'and'thebevel discs 4,."5. In vthis way the frictional resistance-which op- `vlooses the movements axial direction oi 'the beveldiscs 4, 5cm thedrivi'ngshaft lis kept low. A transmission A'of powerfge'nerally fused with gears of this kindvfor instance by Way of a-aidein key or a slidingsplinewoiild 'result in too high a mom-ent of inertia owing Vto the frictionaiv resistance caused byjthetangential 'pressure onthe key groove, 1whereby the f continuitv of 'the' regu- .lation 'of thespeed Wold'become influenced to f The' orivingjoripoiveritransmissionmember I4 in the represente'dexample. lisaii endless cone .belt;,lfl.,j A By' means; of' this belt, theturning inoning surface di'ameterofthe driving belt I4. On the outsides of the bevel`discs I8 and 'I9 are fixedV .arcuate bearing discs Y 20 and 2| which bear against the outer rings of ball bearing assemblies 22 and 23, the latter being rotatably securedtoV j` driving plates 26 and 21 by bolts 24 and 25. Thesei.1 plates 26, 21 are firmly connected to the shaft I5 n as by means of the pins 26 and 21. Springs 2B and 29 are disposed between the members "I8 and A ',i'shed'.- Furthermora the spiral screw springs v`causeavery smooth and bump-free lstarting of 26 Yand I9 and 21 and have their respective endsV disposed in openings in the adjacent members.

and thus the springs serve to transmit the drive between the discs I8 and-I9 and the plates 26 and 21. Springs 28 and 29 assist in the separation of the bevel discs I8, I9 by causing the ball bearings to roll down the curved surfaces 20, 2i upon reduction in the transmitted torque. At the same time they cause both ofthe'bevel discs I8, I9'to be axially pressed towards each other, so that also during the"position of the gear when very little or no power isrbeing transmitted a Suffit cient tension of the belt I4 is ensured.

Figure 2 showssdiagrammatically the `play of movementsbetween Ecurved surfaces 20, 2I and .Y the rollsp22, 23. The curved surfaces are curved in relief and'on one hand they run concentrically' 'with regard to the axis of the shaft while on the other hand they show a variating gradient in axial direction. In the-drawing the curved Vsurface is shown 'in a radial view unrolled on a plane surface.V

The action ofthe mechanism described is as y follows; Whereas in the case of known types of expanding-pulley variable speed gears, the axial changing" of the bevel discs in order to vary the Y speed is caused by a mechanism to be operated at will fromjthe outside, according to this invention the variation kof thev speed will be automatically regulated by the turning moment which is elfi-V cacious on the driven shaft-I5. This is obtained by utilizingthe axial .forces resulting from the wedging effect of thedriving member I4 between the pairs of bevel discs. On the driving shaft I the distance between the two bevel discs 4, 5 and thecorresponding running surface diameter of the driving member I4, is regulated by the axial pressure of the springs and 1 against the bevel discsV 45.- On the driven shaft the distance between the twov bevel` discs I8, I9 and the corresponding running surfacediameter of the drivinglmember I4 is regulated by arcuate inclined surfaces 20 and 2 I, and that inthe reverse sense compared withvthe driving part. Here the balance -is7kept against the axial forces resulting from the wedging effect of the belt I4, the axial forces of reaction of the turning moment on the driven shaft operating on the curved surfaces. This result is obtained by a variable gradient of the curves as shown in the drawing.

The sensitivity of reaction of the gear with regard to variations of the turning moment on the driven shaft depends on the degree of the friction resistance 'which yopposes the axial movements of the bevel discs on the two shafts. Y A transmission of power common with gears of this kind, e. g. by way of a laid-in key or a sliding spline would'in this case result in Vtoo high 'a moment 'of inertia due, to the frictional forces deriving from the tangential pressure exercised on the key groove and therewith the continuity of the regulation control of the number of revolutions would be strongly impaired. In order to avoid these jamming forces of friction the transdition to the axial moving of the bevel discs, a

rotating motion occurs in case of variations of the turning moment. By the spiral movement of the bevel discs on the shaft resulting therefrom, the` frictional 'resistance is considerably diminthe gear. Y

In order to reduce the frictional forces on the curved surfaces of the driven gear as much as possible, the pressure on the bevel discs of these curved surfaces is suitably received by rollers borne by ball bearings. In order to guarantee the reverse run of the rollers in the decreasing sense of thecurved surfaces, especially in the sphere of the `smallest gradient, spiral deformable springs are provided between the bevel discs and the driven shaft, which springs receive a tan-` gential tension if they run up on the curved surfaces in the reverse run, and with the help of this tension the frictional forces resulting fromthe axial resultantof the curve pressure are compensated. Here y too the friction between the shaft and the bevel discs-is considerably diminished by the resulting spiral movement.

On starting Athe gear, the bevel discs 4, 5 of the driving shaft I are positioned at first only a small distance apart. When the turning moment to be transmitted increases,.the tension of the belt I4 will grow in suchY a manner, if a certain degree limit is surpassed, that the driving member I4 whenapproaching the driving shaft will press itself between the'two discs 4,V 5. So these will move apart against the pressure im# parted by the springs 6 and 1. The axial forces of reaction will become effective at the curved surfaces of the driven shaft simultaneously with the reaction of the torque delivered Vfrom the driving shaft. After a certain limit value has been surpassed here too, an unstable balance, caused by the variating gradient of the curves, will be established between the axial forces of the cone drive and the curve pressures resulting from the respective turning moment, in a sense that together with an increasing curve pressure the distance between the bevel discs decreases i. e.,the circular runningV surface diameter cor-V respondingly increases. l y The gear described has the Aadvantage of being of a simple construction aswell as providing variable'vspeeds which are automatically regulated. Among other purposes, it may preferably be used for the actuation of such constructions in which, as for instance in the case of winding-on of flexible cloth bands, paper bands', and textile bands, metal sheets, wires or strip-iron, variable turning moments may occur, while the velocity 'of the band or the like as well as the drive which is imparted to itV must be kept as constant as possible.

I claim:

l. An expandinggpulley, 'variable-speed gear,

axial and rotational directions with respect to said shaft, and the discs of the other pair being similarly mounted on the driven shaft; a V-belt drivingly connecting the two pairs of bevel discs; -a resilient driving connection between the driving shaft and each of the bevel discs mounted thereon, said connections being such as to transmit torque from the driving shaft to said discs and to permit of the aforesaid movements of said discs upon said shaft, said resilient driving connections being such as normally to urge said lbevel discs towards each other; a resilient torquetransmitting connection between each disc of the pair of discs on the driven shaft and said shaft, which torque-transmitting connections are such as to permit limited rotational, axial, and combined rotational and axial movements of the bevel discs on the driven shaft, and means embodied in said torque-transmitting connections between the driven shaft and the discs thereon for causing variations in torque imparted to the driven shaft to move the driven bevel discs thereon axially together or apart in such a manner that the axial movement is proportional to and varies as the torque applied at any instant to the driven bevel discs.

2. An expanding-pulley, variable-speed gear, as claimed in claim 1, wherein the resilient operative driving connection between the driving shaft and the bevel discs mounted thereon comprises two bushes rigidly connected to the driving shaft and a spring drivingly connecting each bevel disc to its associated bush, the said springs being so arranged as to permit of limited rotational, axial and combined rotational and axial movements of the bevel discs.

3. An expanding-pulley, variable-speed gear as claimed in claim 1, wherein the resilient torque-transmitting connection between the pair of -bevel discs on the driven shaft and said shaft comprises two plates, rigidly connected to the driven shaft, a cam interposed between each plate and its associated bevel disc, and a spring for drivingly connecting each plate and bevel disc, said springs permitting of limited rotational, axial, and combined rotational and axial movements of the bevel discs.

4. An expanding-pulley, variable-speed gear, as claimed in claim 1, wherein the resilient operative driving connection between the driving L shaft and the bevel ldiscs mounted thereon comprises two bushes rigidly connected to the driving shaft and a spring drvingly connecting each bevel disc to its associated bush, the said springs being so arranged as to permit of limited rotational and axial movement of the bevel discs; and wherein the resilient torque-transmitting connection between the pair of bevel discs on the driven shaft and said shaft comprises two plates, rigidly connected to the driven shaft, a cam inter- 'posed between each plate and its associated bevel disc, and a spring for connecting each plate and :bevel disc, said springs permitting of limited rotational and axial movement of the bevel discs.

5. An expanding-pulley, variable-speed gear, comprising a driving shaft, a driven shaft, said shafts having smooth surfaces, uninterrupted by keys, splines, pins or the like, two pairs of bevel discs, the discs of one of said :pairs being slidably mounted on the smooth surface of the driving shaft for free movement in axial, rotational, and combined axial and rotational directions with respect to said shaft, and the discs of the other pair being similarly mounted on a smooth surface of the driven shaft; a V-belt drivingly connecting the two pairs of bevel discs; a resilient driving connection between the driving shaft and each of the bevel discs mounted thereon, each of said connections comprising a spring connected between the shaft and the disc and being the only driving connections between said driving shaft and said discs and also being such as to transmit torque from the driving shaft to said discs and to permit of the aforesaid movements of said discs upon said shaft, the springs of said driving connection being such as normally to urge said bevel discs towards each other; a resilient torque-transmitting connection between each of the bevel discs on the driven shaft and said shaft, each of said last named connections comprising a spring connected between the shaft and a disc, which torque-transmitting connections are such as to permit limited rotational, axial, and combined rotational and axial movements of the bevel discs upon the driven shaft, means embodied in said torque-transmitting connections for causing variations in torque imparted to the driven shaft to move the driven bevel discs thereon axially together or apart in such a manner that the axial movement is proportional to and varies as the torque applied at any instant to the 4driven bevel discs.

GOTTFRIED RUEGENBERG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,008,992 Oak July 23, 1935 2,050,358 McElroy Aug. 11, 1936 2,054,564 Quirog Sept. 15, 1936 2,478,289 Lemon Aug. 9, 1949 FOREIGN PATENTS Number Country Date 30,003 Great Britain 1912 132,800 Great Britain Aug. 12, 1920 

